Conduits for transporting fluids and methods of fabricating the same

ABSTRACT

A conduit ( 100 ) for transporting a fluid comprises a first collar ( 102 ), a second collar ( 103 ), and a bellows ( 108 ). The bellows ( 108 ) comprises a corrugated inboard ply ( 110 ), a corrugated outboard ply ( 112 ), and an interstitial space ( 126 ), interposed between the corrugated inboard ply ( 110 ) and the corrugated outboard ply ( 112 ). The conduit additionally comprises a first weld ( 138 ), hermetically coupling the corrugated inboard ply ( 110 ) and a first outer collar portion ( 104 ), a second weld ( 134 ), hermetically coupling the corrugated outboard ply ( 112 ) and a first inner collar portion ( 106 ), a third weld ( 186 ), hermetically coupling the corrugated inboard ply ( 110 ) and a second outer collar portion ( 105 ), a fourth weld ( 184 ), hermetically coupling the corrugated outboard ply ( 112 ) and a second inner collar portion ( 107 ), and a first sensor ( 116 ), communicatively coupled with the interstitial space ( 126 ).

GOVERNMENT LICENSE RIGHTS

This invention was made with Government support under HR0011-17-9-0001awarded by Defense Advanced Research Projects Agency. The government hascertain rights in this invention.

TECHNICAL FIELD

The present disclosure relates to conduits for transporting fluids andmethods of fabricating such conduits

BACKGROUND

Flexible conduits, used in cryogenic propulsion systems, are susceptibleto manufacturing variances and incidental damage. If not timelyidentified, failure of a flexible conduit, such as apressurized-propellant feed line, could potentially lead to damage ofthe main propulsion system.

SUMMARY

Accordingly, apparatuses and methods, intended to address at least theabove-identified concerns, would find utility.

The following is a non-exhaustive list of examples, which may or may notbe claimed, of the subject matter, disclosed herein.

One example of the subject matter, disclosed herein, relates to aconduit for transporting a fluid. The conduit comprises a first collarthat comprises a first outer collar portion and a first inner collarportion, threadably coupled with the first outer collar portion. Theconduit also comprises a second collar that comprises a second outercollar portion and a second inner collar portion, threadably coupledwith the second outer collar portion. The conduit further comprises abellows that comprises a central axis, a corrugated outboard ply, acorrugated inboard ply, interposed between the corrugated outboard plyand the central axis, and an interstitial space, interposed between thecorrugated inboard ply and the corrugated outboard ply. The conduitadditionally comprises a first weld, hermetically coupling thecorrugated inboard ply and the first outer collar portion. The conduitalso comprises a second weld, hermetically coupling the corrugatedoutboard ply and the first inner collar portion. The conduit furthercomprises a third weld, hermetically coupling the corrugated inboard plyand the second outer collar portion. The conduit additionally comprisesa fourth weld, hermetically coupling the corrugated outboard ply and thesecond inner collar portion. The conduit also comprises a first sensor,communicatively coupled with the interstitial space.

The conduit provides a compliant structure for transportation of fluids,such as cryogenic fuels, that accommodates displacements encounteredduring operation. The first sensor, being communicatively coupled withthe interstitial space, allows the first sensor to monitor conditionswithin the interstitial space. In particular, the sensor enablesdetection of leaks in the corrugated inboard ply by detecting changes inconditions within the interstitial space. The threadable couplingbetween the first outer collar portion and the first inner collarportion facilitates hermetical coupling of the first outer collarportion and the first inner collar portion while allowing the firstouter collar portion to be separately formed from and interconnected tothe first inner collar portion, which enables the bellows to behermetically coupled to the first collar in a simple and efficientmanner. Similarly, the threadable coupling between the second outercollar portion and the second inner collar portion facilitateshermetical coupling of the second outer collar portion and the secondinner collar portion while allowing the second outer collar portion tobe separately formed from and interconnected to the second inner collarportion, which enables the bellows to be hermetically coupled to thesecond collar in a simple and efficient manner. The first weld promotesa strong, reliable, and sealed connection between the corrugated inboardply and the first outer collar portion. The second weld promotes astrong, reliable, and sealed connection between the corrugated outboardply and the first inner collar portion. The third weld promotes astrong, reliable, and sealed connection between the corrugated inboardply and the second outer collar portion. The fourth weld promotes astrong, reliable, and sealed connection between the corrugated outboardply and the second inner collar portion. Communicatively coupling theinterstitial space with the first sensor allows leaks of fluid or gasinto the interstitial space through the corrugated inboard ply to bedetected at a location, external to the first collar and the secondcollar.

Another example of the subject matter, disclosed herein, relates to aconduit for transporting a fluid. The conduit comprises a first collarthat comprises a first outer collar portion and a first inner collarportion, threadably coupled with the first outer collar portion. Theconduit also comprises a bellows that comprises a central axis, acorrugated outboard ply, a corrugated inboard ply, interposed betweenthe corrugated outboard ply and the central axis, and an interstitialspace, interposed between the corrugated inboard ply and the corrugatedoutboard ply. The conduit further comprises a first weld, hermeticallycoupling the corrugated inboard ply and the first outer collar portion.The conduit additionally comprises a second weld, hermetically couplingthe corrugated outboard ply and the first inner collar portion. Theconduit also comprises a first sensor, communicatively coupled with theinterstitial space.

The conduit provides a compliant structure for transmission of fluids,such as cryogenic fuels, that accommodates displacements encounteredduring operation. The first sensor, being communicatively coupled withthe interstitial space, allows the first sensor to monitor conditionswithin the interstitial space. In particular, the first sensor enablesdetection of leaks in the corrugated inboard ply by detecting changes inconditions within the interstitial space. The threadable couplingbetween the first outer collar portion and the first inner collarportion facilitates hermetical coupling of the first outer collarportion and the first inner collar portion while allowing the firstouter collar portion to be separately formed from and interconnected tothe first inner collar portion, which enables the bellows to behermetically coupled to the first collar in a simple and efficientmanner. The first weld promotes a strong, reliable, and sealedconnection between the corrugated inboard ply and the first outer collarportion. The second weld promotes a strong, reliable, and sealedconnection between the corrugated outboard ply and the first innercollar portion. Communicatively coupling the interstitial space with thefirst sensor allows leaks of fluid or gas into the interstitial spacethrough the corrugated inboard ply to be detected at a location,external to the first collar.

Another example of the subject matter, disclosed herein, relates to amethod of fabricating a conduit. The method comprises attaching a firsttubular-outboard-ply end of a tubular outboard ply to a first innercollar portion of a first collar with a second weld. The method alsocomprises attaching a second tubular-outboard-ply end of the tubularoutboard ply, which is axially opposite the first tubular-outboard-plyend of the tubular outboard ply, to a second inner collar portion of asecond collar with a fourth weld. The method further comprises insertinga tubular inboard ply into the tubular outboard ply and advancing thetubular inboard ply along an interior of the tubular outboard ply untila first tubular-inboard-ply end of the tubular inboard ply protrudes afirst distance past the first inner collar portion, and a secondtubular-inboard-ply end protrudes a second distance past the secondinner collar portion. The first distance is greater than a firstpredetermined distance and the second distance is greater than a secondpredetermined distance. The method additionally comprises simultaneouslycorrugating the tubular inboard ply and the tubular outboard ply to forma bellows. The bellows has a central axis and comprises a corrugatedoutboard ply, a corrugated inboard ply, and an interstitial space,interposed between the corrugated inboard ply and the corrugatedoutboard ply. The corrugated outboard ply is formed from the tubularoutboard ply, and the corrugated inboard ply is formed from the tubularinboard ply. The method also comprises trimming a firstcorrugated-inboard-ply end of the corrugated inboard ply, correspondingto the first tubular-inboard-ply end of the tubular inboard ply, tocreate a trimmed first corrugated-inboard-ply end that protrudes thefirst predetermined distance past the first inner collar portion. Themethod further comprises trimming a second corrugated-inboard-ply end ofthe corrugated inboard ply, corresponding to the secondtubular-inboard-ply end of the tubular inboard ply, to create a trimmedsecond corrugated-inboard-ply end that protrudes the secondpredetermined distance past the second inner collar portion. The methodadditionally comprises threadably interconnecting the first inner collarportion and a first outer collar portion of the first collar. The methodalso comprises threadably interconnecting the second inner collarportion and a second outer collar portion of the second collar. Themethod further comprises attaching the trimmed firstcorrugated-inboard-ply end of the corrugated inboard ply to the firstouter collar portion with a first weld. The method additionallycomprises attaching the trimmed second corrugated-inboard-ply end of thecorrugated inboard ply to the second outer collar portion with a thirdweld. The method also comprises communicatively coupling a first sensorwith the interstitial space.

The method facilitates fabrication of the conduit in an efficient andsimple manner. The conduit provides a compliant structure fortransmission of fluids, such as cryogenic fuels, that accommodatesdisplacements encountered during operation. The first sensor, beingcommunicatively coupled with the interstitial space, allows the firstsensor to monitor conditions within the interstitial space. Thethreadable coupling between the first outer collar portion and the firstinner collar portion facilitates hermetical coupling of the first outercollar portion and the first inner collar portion while allowing thefirst outer collar portion to be separately formed from andinterconnected to the first inner collar portion, which enables thebellows to be hermetically coupled to the first collar in a simple andefficient manner. Similarly, the threadable coupling between the secondouter collar portion and the second inner collar portion facilitateshermetical coupling of the second outer collar portion and the secondinner collar portion while allowing the second outer collar portion tobe separately formed from and interconnected to the second inner collarportion, which enables the bellows to be hermetically coupled to thesecond collar in a simple and efficient manner. The first weld promotesa strong, reliable, and sealed connection between the corrugated inboardply and the first outer collar portion. The second weld promotes astrong, reliable, and sealed connection between the corrugated outboardply and the first inner collar portion. The third weld promotes astrong, reliable, and sealed connection between corrugated the inboardply and the second outer collar portion. The fourth weld promotes astrong, reliable, and sealed connection between the corrugated outboardply and the second inner collar portion. Advancing the tubular inboardply along an interior of the tubular outboard ply until the firsttubular-inboard-ply end of the tubular inboard ply protrudes a firstdistance past the first inner collar portion, and the secondtubular-inboard-ply end protrudes a second distance past the secondinner collar portion accommodates the reduction in the length of thetubular inboard ply after the tubular inboard ply is corrugated.Trimming the first corrugated-inboard-ply end of the corrugated inboardply and trimming the second corrugated-inboard-ply end of the corrugatedinboard ply promotes achieving a desired length of the corrugatedinboard ply after corrugation of the tubular inboard ply.Communicatively coupling the interstitial space with the first sensorallows leaks of fluid or gas into interstitial space the through thecorrugated inboard ply to be detected at a location, external to thefirst collar and the second collar.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described one or more examples of the present disclosure ingeneral terms, reference will now be made to the accompanying drawings,which are not necessarily drawn to scale, and wherein like referencecharacters designate the same or similar parts throughout the severalviews, and wherein:

FIGS. 1A, 1B, and 1C, collectively, are a block diagram of a conduit fortransporting a fluid, according to one or more examples of the presentdisclosure;

FIG. 2 is a schematic, perspective, sectional view of a first collarportion of the conduit of FIGS. 1A, 1B, and 1C, according to one or moreexamples of the present disclosure;

FIG. 3 is a schematic, perspective, sectional view of the conduit ofFIGS. 1A, 1B, and 1C, according to one or more examples of the presentdisclosure;

FIG. 4 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 5 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 6 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 7 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 8 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 9 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 10 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 11 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 12 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIGS. 13A-13E, collectively, are a block diagram of a method offabricating a conduit of FIGS. 1A, 1B, and 1C, according to one or moreexamples of the present disclosure;

FIG. 14 is a block diagram of aircraft production and servicemethodology; and

FIG. 15 is a schematic illustration of an aircraft.

DETAILED DESCRIPTION

In FIGS. 1A, 1B, and 1C, referred to above, solid lines, if any,connecting various elements and/or components may represent mechanical,electrical, fluid, optical, electromagnetic and other couplings and/orcombinations thereof. As used herein, “coupled” means associateddirectly as well as indirectly. For example, a member A may be directlyassociated with a member B, or may be indirectly associated therewith,e.g., via another member C. It will be understood that not allrelationships among the various disclosed elements are necessarilyrepresented. Accordingly, couplings other than those depicted in theblock diagrams may also exist. Dashed lines, if any, connecting blocksdesignating the various elements and/or components represent couplingssimilar in function and purpose to those represented by solid lines;however, couplings represented by the dashed lines may either beselectively provided or may relate to alternative examples of thepresent disclosure. Likewise, elements and/or components, if any,represented with dashed lines, indicate alternative examples of thepresent disclosure. One or more elements shown in solid and/or dashedlines may be omitted from a particular example without departing fromthe scope of the present disclosure. Environmental elements, if any, arerepresented with dotted lines. Virtual (imaginary) elements may also beshown for clarity. Those skilled in the art will appreciate that some ofthe features illustrated in FIGS. 1A, 1B, and 1C may be combined invarious ways without the need to include other features described inFIGS. 1A, 1B, and 1C, other drawing figures, and/or the accompanyingdisclosure, even though such combination or combinations are notexplicitly illustrated herein. Similarly, additional features notlimited to the examples presented, may be combined with some or all ofthe features shown and described herein.

In FIGS. 13A-13E and 14, referred to above, the blocks may representoperations and/or portions thereof and lines connecting the variousblocks do not imply any particular order or dependency of the operationsor portions thereof. Blocks represented by dashed lines indicatealternative operations and/or portions thereof. Dashed lines, if any,connecting the various blocks represent alternative dependencies of theoperations or portions thereof. It will be understood that not alldependencies among the various disclosed operations are necessarilyrepresented. FIGS. 13A-13E and 14 and the accompanying disclosuredescribing the operations of the method(s) set forth herein should notbe interpreted as necessarily determining a sequence in which theoperations are to be performed. Rather, although one illustrative orderis indicated, it is to be understood that the sequence of the operationsmay be modified when appropriate. Accordingly, certain operations may beperformed in a different order or simultaneously. Additionally, thoseskilled in the art will appreciate that not all operations describedneed be performed.

In the following description, numerous specific details are set forth toprovide a thorough understanding of the disclosed concepts, which may bepracticed without some or all of these particulars. In other instances,details of known devices and/or processes have been omitted to avoidunnecessarily obscuring the disclosure. While some concepts will bedescribed in conjunction with specific examples, it will be understoodthat these examples are not intended to be limiting.

Unless otherwise indicated, the terms “first,” “second,” etc. are usedherein merely as labels, and are not intended to impose ordinal,positional, or hierarchical requirements on the items to which theseterms refer. Moreover, reference to, e.g., a “second” item does notrequire or preclude the existence of, e.g., a “first” or lower-numbereditem, and/or, e.g., a “third” or higher-numbered item.

Reference herein to “one example” means that one or more feature,structure, or characteristic described in connection with the example isincluded in at least one implementation. The phrase “one example” invarious places in the specification may or may not be referring to thesame example.

As used herein, a system, apparatus, structure, article, element,component, or hardware “configured to” perform a specified function isindeed capable of performing the specified function without anyalteration, rather than merely having potential to perform the specifiedfunction after further modification. In other words, the system,apparatus, structure, article, element, component, or hardware“configured to” perform a specified function is specifically selected,created, implemented, utilized, programmed, and/or designed for thepurpose of performing the specified function. As used herein,“configured to” denotes existing characteristics of a system, apparatus,structure, article, element, component, or hardware which enable thesystem, apparatus, structure, article, element, component, or hardwareto perform the specified function without further modification. Forpurposes of this disclosure, a system, apparatus, structure, article,element, component, or hardware described as being “configured to”perform a particular function may additionally or alternatively bedescribed as being “adapted to” and/or as being “operative to” performthat function.

Illustrative, non-exhaustive examples, which may or may not be claimed,of the subject matter according the present disclosure are providedbelow.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, conduit 100 for transporting a fluid is disclosed. Conduit 100comprises first collar 102 that comprises first outer collar portion 104and first inner collar portion 106, threadably coupled with first outercollar portion 104. Conduit 100 also comprises second collar 103 thatcomprises second outer collar portion 105 and second inner collarportion 107, threadably coupled with second outer collar portion 105.Conduit 100 further comprises bellows 108 that comprises central axis180, corrugated outboard ply 112, corrugated inboard ply 110, interposedbetween corrugated outboard ply 112 and central axis 180, andinterstitial space 126, interposed between corrugated inboard ply 110and corrugated outboard ply 112. Conduit 100 additionally comprisesfirst weld 138, hermetically coupling corrugated inboard ply 110 andfirst outer collar portion 104. Conduit 100 also comprises second weld134, hermetically coupling corrugated outboard ply 112 and first innercollar portion 106. Conduit 100 further comprises third weld 186,hermetically coupling corrugated inboard ply 110 and second outer collarportion 105. Conduit 100 additionally comprises fourth weld 184,hermetically coupling corrugated outboard ply 112 and second innercollar portion 107. Conduit 100 also comprises first sensor 116,communicatively coupled with interstitial space 126. The precedingsubject matter of this paragraph characterizes example 1 of the presentdisclosure.

Conduit 100 provides a compliant structure for transportation of fluids,such as cryogenic fuels, that accommodates displacements encounteredduring operation. First sensor 116, being communicatively coupled withinterstitial space 126, allows first sensor 116 to monitor conditionswithin interstitial space 126. In particular, first sensor 116 enablesdetection of leaks in corrugated inboard ply 110 by detecting changes inconditions within interstitial space 126. The threadable couplingbetween first outer collar portion 104 and first inner collar portion106 facilitates hermetical coupling of first outer collar portion 104and first inner collar portion 106 while allowing first outer collarportion 104 to be separately formed from and interconnected to firstinner collar portion 106, which enables bellows 108 to be hermeticallycoupled to first collar 102 in a simple and efficient manner. Similarly,the threadable coupling between second outer collar portion 105 andsecond inner collar portion 107 facilitates hermetical coupling ofsecond outer collar portion 105 and second inner collar portion 107while allowing second outer collar portion 105 to be separately formedfrom and interconnected to second inner collar portion 107, whichenables bellows 108 to be hermetically coupled to second collar 103 in asimple and efficient manner. First weld 138 promotes a strong, reliable,and sealed connection between corrugated inboard ply 110 and first outercollar portion 104. Second weld 134 promotes a strong, reliable, andsealed connection between corrugated outboard ply 112 and first innercollar portion 106. Third weld 186 promotes a strong, reliable, andsealed connection between corrugated inboard ply 110 and second outercollar portion 105. Fourth weld 184 promotes a strong, reliable, andsealed connection between corrugated outboard ply 112 and second innercollar portion 107. Communicatively coupling interstitial space 126 withfirst sensor 116 allows leaks of fluid or gas into interstitial space126 through corrugated inboard ply 110 to be detected at a location,external to first collar 102 and second collar 103.

First weld 138, second weld 134, third weld 186, and fourth weld 184help to respectively hermetically couple first end 160 of bellows 108 tofirst collar 102 and second end 162 of bellows 108, which is oppositefirst end 160 of bellows, to second collar 103. In some examples, eachof first weld 138, second weld 134, third weld 186, and fourth weld 184is a homogenous weld that includes filler material. Homogenous welds arehelpful when welding relatively thin parts, such as corrugated inboardply 110 and corrugated outboard ply 112. In one or more examples, thefiller material is a material with properties similar to those of thematerial of first outer collar portion 104, first inner collar portion106, second outer collar portion 105, and second inner collar portion107. According to certain examples, each of first outer collar portion104, first inner collar portion 106, second outer collar portion 105,second inner collar portion 107, corrugated inboard ply 110, andcorrugated outboard ply 112 is made of an austeniticnickel-chromium-based superalloy, such as Inconel®. Each of corrugatedinboard ply 110 and corrugated outboard ply 112 has a thickness of about0.012 inches, in some examples.

According to some examples, one or more of first outer collar portion104, first inner collar portion 106, second outer collar portion 105,and second inner collar portion 107 is manufactured using subtractivemanufacturing techniques, such as machining. In other examples, one ormore of first outer collar portion 104, first inner collar portion 106,second outer collar portion 105, and second inner collar portion 107 ismanufactured using additive manufacturing techniques. In yet otherexamples, one or more of first outer collar portion 104, first innercollar portion 106, second outer collar portion 105, and second innercollar portion 107 is manufactured using forging or casting techniques.

In some examples, first collar 102 is different than second collar 103.In one or more examples, first fluid flow port 132 of first collar 102is of a first type, for fluidly coupling to a first component, andsecond fluid flow port 133 of second collar 103 is of a second type, forfluidly coupling to a second component, different than the firstcomponent. Each of first fluid flow port 132 and second fluid flow port133 defines an aperture through which fluid flows into or out of conduit100. In some examples, one of first fluid flow port 132 or second fluidflow port 133 is a nozzle.

Bellows 108 comprises corrugations 158 that help to facilitatecompliance of bellows 108. For example, corrugations 158 allow bellows108 to expand and retract, radially and longitudinally, relative tocentral axis 180, in response to changes in internal and externalconditions relative to conduit 100 (e.g., changes in pressure,temperature, and geometry). Additionally, bellows 108 defines fluid flowchannel 128, through which fluid is flowable.

In one or more examples, first sensor 116 is any one of various sensorsused to detect the presence of a chemical or a pressure change. In oneof more examples, first sensor 116 is one or more of a micro-fuel cell,contactless oxygen sensor spots, oxygen sensor foil, and oxygen probes.

Welds are continuous or annular shaped in one or more examples.Additionally, in one or more example, welds have closed shapes. As usedherein, “hermetically coupled with a weld” means the weld is continuousand forms a closed shape.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, at least a part of a portion of corrugated outboard ply 112,proximate second weld 134, is closer to central axis 180 of bellows 108than second weld 134. At least a part of a portion of corrugatedoutboard ply 112, proximate fourth weld 184, is closer to central axis180 of bellows 108 than fourth weld 184. The preceding subject matter ofthis paragraph characterizes example 2 of the present disclosure,wherein example 2 also includes the subject matter according to example1, above.

At least part of a portion of corrugated outboard ply 112, proximatesecond weld 134, being closer to central axis 180 of bellows 108 thansecond weld 134, ensures second weld 134 does not obstruct interstitialspace 126. Similarly, at least part of a portion of corrugated outboardply 112, proximate fourth weld 184, being closer to central axis 180 ofbellows 108 than fourth weld 184, ensures fourth weld 184 does notobstruct interstitial space 126.

Referring generally to FIG. 1A and particularly to, e.g., FIGS. 2 and 3,first collar 102 further comprises first channel 118, passing throughone of first outer collar portion 104 or first inner collar portion 106.First channel 118 is cross-sectionally circumferentially closed. Firstchannel 118 is communicatively coupled with interstitial space 126 ofbellows 108. First sensor 116 is communicatively coupled with firstchannel 118 of first collar 102. The preceding subject matter of thisparagraph characterizes example 3 of the present disclosure, whereinexample 3 also includes the subject matter according to example 1 or 2,above.

Communicatively coupling interstitial space 126 with first sensor 116,via first channel 118 passing through one of first outer collar portion104 or first inner collar portion 106, allows leaks of fluid or gas intointerstitial space 126 through corrugated inboard ply 110 to be detectedat any of various locations external to first collar 102, which helps tosimplify the assembly and design of first collar 102 of conduit 100.

As defined in relation to first channel 118, which is, for example, aport or a hole, “cross-sectionally circumferentially closed” means thatthe circumference of any cross-section of first channel 118 that lies ina plane, perpendicular to a central axis of first channel 118, has aclosed shape. A closed shape is a space that is fully enclosed by anunbroken line or contour.

Referring generally to FIG. 1A and particularly to, e.g., FIGS. 2 and 3,first channel 118 passes through first outer collar portion 104 of firstcollar 102. The preceding subject matter of this paragraph characterizesexample 4 of the present disclosure, wherein example 4 also includes thesubject matter according to example 3, above.

First channel 118, passing through first outer collar portion 104 offirst collar 102, allows first sensor 116 to be located on first outercollar portion 104, which helps to free up space on first inner collarportion 106 for attachment of sheath 130.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, the pressure in interstitial space 126 and in first channel 118is no more than 15 pounds per square inch (psi). The preceding subjectmatter of this paragraph characterizes example 5 of the presentdisclosure, wherein example 5 also includes the subject matter accordingto example 3 or 4, above.

When conduit 100 is used in space, maintaining pressure in interstitialspace 126 at or below 15 psi provides controlled separation betweencorrugated inboard ply 110 and corrugated outboard ply 112, whichprevents corrugated inboard ply 110 and corrugated outboard ply 112 frompressing against each other excessively. Preventing corrugated inboardply 110 and corrugated outboard ply 112 from pressing against each otherexcessively helps facilitate transfer, to first sensor 116, of any fluid(e.g., propellant) that has leaked into interstitial space 126.Furthermore, controlled separation between corrugated inboard ply 110and corrugated outboard ply 112 helps to reduce scuffing betweencorrugated inboard ply 110 and corrugated outboard ply 112. As usedherein, pounds per square inch (psi) is absolute pressure.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, the pressure in interstitial space 126 and in first channel 118is no more than 5 psi. The preceding subject matter of this paragraphcharacterizes example 6 of the present disclosure, wherein example 6also includes the subject matter according to example 5, above.

Maintaining pressure in interstitial space 126 at or below 5 psi ensurespressure in interstitial space 126 is not excessive when conduit 100 isused in space. Additionally, providing some pressure at or below 5 psiin interstitial space 126 provides some controlled separation betweencorrugated inboard ply 110 and corrugated outboard ply 112.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, first collar 102 further comprises first cavity 124, locatedbetween first outer collar portion 104 and first inner collar portion106. Second collar 103 further comprises second cavity 125, locatedbetween second outer collar portion 105 and second inner collar portion107. First channel 118 is communicatively coupled with first cavity 124.First cavity 124 has an annular shape and is communicatively coupledwith interstitial space 126. Second cavity 125 has an annular shape andis communicatively coupled with interstitial space 126. The precedingsubject matter of this paragraph characterizes example 7 of the presentdisclosure, wherein example 7 also includes the subject matter accordingto any one of examples 3 to 6, above.

First cavity 124, having an annular shape and being communicativelycoupled with interstitial space 126, and second cavity 125, also havingan annular shape and also being communicatively coupled withinterstitial space 126, helps to distribute fluid, leaked intointerstitial space 126 at any of various locations about a circumferenceof interstitial space 126, to first channel 118 and first sensor 116.Additionally, first cavity 124 helps to ensure path from interstitialspace 126 to first channel 118 is unobstructed.

Referring generally to FIG. 1B and particularly to, e.g., FIG. 3,conduit 100 further comprises second sensor 117. Second collar 103further comprises second channel 119, passing through one of secondouter collar portion 105 or second inner collar portion 107. Secondchannel 119 is cross-sectionally circumferentially closed. Secondchannel 119 is communicatively coupled with interstitial space 126 ofbellows 108. Second sensor 117 is communicatively coupled with secondchannel 119 of second collar 103. The preceding subject matter of thisparagraph characterizes example 8 of the present disclosure, whereinexample 8 also includes the subject matter according to example 7,above.

Communicatively coupling interstitial space 126 with second sensor 117,via second channel 119 passing through one of second outer collarportion 105 or second inner collar portion 107, allows leaks of fluid orgas into interstitial space 126 through corrugated inboard ply 110 to bedetected at any of various locations external to second collar 103,which helps to simplify the assembly and design of second collar 103 ofconduit 100. Additionally, second sensor 117, being communicativelycoupled with interstitial space 126 along with first sensor 116,promotes redundant detection of leakage through corrugated inboard ply110. In one or more examples, second sensor 117 is able to detect achange in pressure or chemical composition in interstitial space 126that is not detectable by first sensor 116 for various reasons, such as,for example, fluid or gas leaked from corrugated inboard ply 110 doesnot reach first sensor 116 or first sensor 116 is disabled.

First sensor 116 is the same type of sensor as second sensor 117 in someexamples. In other examples, first sensor 116 is a different type ofsensor than second sensor 117. In one or more examples, first sensor 116detects chemical changes in interstitial space 126, and second sensor117 detects pressure changes in interstitial space 126, or vice versa.Employing sensors of different types is helpful when a first type ofchange in interstitial space 126 is undetectable and a second type ofchange in interstitial space 126 is detectable or is more detectablethan the first type of change.

In one or more examples, second sensor 117 is any of various sensorsused to detect the presence of a chemical or a pressure change. In oneor more examples, second sensor 117 is one or more of a micro-fuel cell,contactless oxygen sensor spots, oxygen sensor foil, and oxygen probes.

Referring generally to FIG. 1B and particularly to, e.g., FIG. 3, secondchannel 119 passes through second outer collar portion 105 of secondcollar 103. The preceding subject matter of this paragraph characterizesexample 9 of the present disclosure, wherein example 9 also includes thesubject matter according to example 8, above.

Second channel 119, passing through second outer collar portion 105 ofsecond collar 103, allows second sensor 117 to be located on secondouter collar portion 105, which helps to free up space on second innercollar portion 107 for attachment of sheath 130.

Referring generally to FIG. 1B and particularly to, e.g., FIG. 3, secondsensor 117 is configured to detect a pressure change in interstitialspace 126. The preceding subject matter of this paragraph characterizesexample 10 of the present disclosure, wherein example 10 also includesthe subject matter according to example 8 or 9, above.

Pressurized fluid leaking from corrugated inboard ply 110 can cause achange in pressure in interstitial space 126. Second sensor 117, beingconfigured to detect a pressure change in interstitial space 126, allowsleakage of fluid from corrugated inboard ply 110 to be detected.Furthermore, second sensor 117, being configured to detect a pressurechange in interstitial space 126, is agnostic to the type of fluidtransmitted through conduit 100 and leaking from corrugated inboard ply110, in one or more examples, which helps to increase the versatility ofconduit 100.

Referring generally to FIG. 1B and particularly to, e.g., FIG. 3, secondsensor 117 is configured to detect a chemical change within interstitialspace 126. The preceding subject matter of this paragraph characterizesexample 11 of the present disclosure, wherein example 11 also includesthe subject matter according to example 8 or 9, above.

In one of more examples, fluid, leaking through corrugated inboard ply110, causes a change in chemical composition in interstitial space 126as the fluid enters and occupies interstitial space 126. Second sensor117, being configured to detect a change in chemical composition ininterstitial space 126, allows leakage of fluid from corrugated inboardply 110 to be detected. Furthermore, second sensor 117, being configuredto detect a change in chemical composition in interstitial space 126, isagnostic to the pressure of fluid transmitted through conduit 100 andpressure of fluid in interstitial space 126, in one or more examples,which helps to increase the versatility of conduit 100.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, bellows 108 further comprises second corrugated outboard ply114. Corrugated outboard ply 112 is interposed between corrugatedinboard ply 110 and second corrugated outboard ply 114. Secondcorrugated outboard ply 114 is hermetically coupled to first innercollar portion 106 by second weld 134 and is hermetically coupled tosecond inner collar portion 107 by fourth weld 184. The precedingsubject matter of this paragraph characterizes example 12 of the presentdisclosure, wherein example 12 also includes the subject matteraccording to any one of examples 1 to 11, above.

Second weld 134 promotes a strong, reliable, and sealed connectionbetween corrugated outboard ply 112, second corrugated outboard ply 114,and first inner collar portion 106. Fourth weld 184 promotes a strong,reliable, and sealed connection between corrugated outboard ply 112,second corrugated outboard ply 114, and second inner collar portion 107.Second corrugated outboard ply 114 provides a redundant outboard ply,which, in one or more examples, promotes fault tolerance of conduit 100by enabling conduit 100 to continue to operate if corrugated outboardply 112 fails. Additionally, second corrugated outboard ply 114 protectscorrugated outboard ply 112 from abrasions caused by objects outboard ofcorrugated outboard ply 112, such as sheath 130.

Second corrugated outboard ply 114 is made of an austeniticnickel-chromium-based superalloy, such as Inconel®, in some examples.Moreover, in certain examples, second corrugated outboard ply 114 has athickness of about 0.012 inches.

Each of second weld 134 and fourth weld 184 is a single weld, in one ormore examples. In one or more examples, second weld 134 is split up intotwo separate welds, each attaching a corresponding one of corrugatedoutboard ply 112 and second corrugated outboard ply 114 to first innercollar portion 106. Similarly, in one or more examples, fourth weld 184is split up into two separate welds each welding a corresponding one ofcorrugated outboard ply 112 and second corrugated outboard ply 114 tosecond inner collar portion 107.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, first weld 138 is offset from second weld 134 along centralaxis 180 of bellows 108. Third weld 186 is offset from fourth weld 184along central axis 180 of bellows 108. The preceding subject matter ofthis paragraph characterizes example 13 of the present disclosure,wherein example 13 also includes the subject matter according to any oneof examples 1 to 12, above.

First weld 138, being offset from second weld 134 along central axis 180of bellows 108, helps to ensure first sensor 116 remains communicativelycoupled with interstitial space 126 by ensuring first weld 138 is clearof second weld 134 in axial direction along central axis 180. Third weld186, being offset from fourth weld 184 along central axis 180 of bellows108, helps to ensure interstitial space 126 is open to second cavity 125by ensuring third weld 186 is clear of fourth weld 184 in axialdirection along central axis 180.

For purposes of this disclosure, “along” means coincident with orparallel to.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, first weld 138 is offset from second weld 134 along an axis,perpendicular to central axis 180 of bellows 108, and is closer tocentral axis 180 than second weld 134. Third weld 186 is offset fromfourth weld 184 along an axis, perpendicular to central axis 180 ofbellows 108, and is closer to central axis 180 than fourth weld 184. Thepreceding subject matter of this paragraph characterizes example 14 ofthe present disclosure, wherein example 14 also includes the subjectmatter according to any one of examples 1 to 13, above.

First weld 138, being offset from second weld 134 along an axis,perpendicular to central axis 180 of bellows 108 and being closer tocentral axis 180 than second weld 134, helps to ensure first sensor 116remains communicatively coupled with interstitial space 126 by ensuringfirst weld 138 is clear of second weld 134 in radial direction relativeto central axis 180. Third weld 186, being offset from fourth weld 184along an axis, perpendicular to central axis 180 of bellows 108 andbeing closer to central axis 180 than fourth weld 184, helps to ensureinterstitial space 126 is open to second cavity 125 by ensuring thirdweld 186 is clear of fourth weld 184 in radial direction relative tocentral axis 180.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2-12, first outer collar portion 104 comprises first threads 152. Firstinner collar portion 106 comprises second threads 154, threadablyengaged with first threads 152 of first outer collar portion 104 so thatfirst abutment interface 139 is formed between first outer collarportion 104 and first inner collar portion 106. Second outer collarportion 105 comprises third threads 142. Second inner collar portion 107comprises fourth threads 143, threadably engaged with third threads 142of second outer collar portion 105 so that second abutment interface 141is formed between second outer collar portion 105 and second innercollar portion 107. The preceding subject matter of this paragraphcharacterizes example 15 of the present disclosure, wherein example 15also includes the subject matter according to any one of examples 1 to14, above.

Threadable engagement between first threads 152 and second threads 154enables first outer collar portion 104 to be coupled to first innercollar portion 106 in a simple and efficient manner. Similarly,threadable engagement between third threads 142 and fourth threads 143enables second outer collar portion 105 to be coupled to second innercollar portion 107 in a simple and efficient manner. First abutmentinterface 139 and second abutment interface 141 promote hermeticalcoupling of first outer collar portion 104 and first inner collarportion 106, and second outer collar portion 105 and second inner collarportion 107, respectively, at locations away from first threads 152 andsecond threads 154 and away from third threads 142 and fourth threads143, which allows hermetical sealing of first outer collar portion 104and first inner collar portion 106, and second outer collar portion 105and second inner collar portion 107, to be performed separately fromthreadably engagement between first outer collar portion 104 and firstinner collar portion 106, and second outer collar portion 105 and secondinner collar portion 107.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2, 3, 11, and 12, first collar 102 further comprises fifth weld 136,hermetically coupling first outer collar portion 104 and first innercollar portion 106 along first abutment interface 139 between firstouter collar portion 104 and first inner collar portion 106. Secondcollar 103 further comprises sixth weld 137, hermetically couplingsecond outer collar portion 105 and second inner collar portion 107along second abutment interface 141 between second outer collar portion105 and second inner collar portion 107. The preceding subject matter ofthis paragraph characterizes example 16 of the present disclosure,wherein example 16 also includes the subject matter according to example15, above.

Fifth weld 136 enables hermetical coupling of first outer collar portion104 and first inner collar portion 106. Similarly, sixth weld 137enables hermetical coupling of second outer collar portion 105 andsecond inner collar portion 107. First threads 152 and second threads154 enable a strong mechanical coupling of first outer collar portion104 and first inner collar portion 106, which allows fifth weld 136 tobe configured primarily for hermetical coupling of first outer collarportion 104 and first inner collar portion 106. Accordingly, in one ormore examples, fifth weld 136 is relatively smaller, or be of adifferent type of weld, than a weld for providing the sole mechanicalcoupling of first outer collar portion 104 and first inner collarportion 106. Third threads 142 and fourth threads 143 enable a strongmechanical coupling of second outer collar portion 105 and second innercollar portion 107, which allows sixth weld 137 to be configuredprimarily for hermetical coupling of second outer collar portion 105 andsecond inner collar portion 107. Accordingly, in one or more examples,sixth weld 137 is relatively smaller, or be of a different type of weld,than a weld for providing the sole mechanical coupling of second outercollar portion 105 and second inner collar portion 107. In someexamples, each of fifth weld 136 and sixth weld 137 is an autogenousweld.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, conduit 100 further comprises sheath 130 that comprisesreinforcement layer 187. Corrugated outboard ply 112 is interposedbetween sheath 130 and central axis 180. The preceding subject matter ofthis paragraph characterizes example 17 of the present disclosure,wherein example 17 also includes the subject matter according to any oneof examples 1 to 16, above.

Reinforcement layer 187 of sheath 130 helps to protect bellows 108 fromexternal objects.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, sheath 130 is coupled to first inner collar portion 106 offirst collar 102 and to second inner collar portion 107 of second collar103. The preceding subject matter of this paragraph characterizesexample 18 of the present disclosure, wherein example 18 also includesthe subject matter according to example 17, above.

Coupling sheath 130 to first inner collar portion 106 of first collar102 and second inner collar portion 107 of second collar 103 ensuresentirety of outer periphery of bellows 108 is protected. Additionally,coupling sheath 130 to first inner collar portion 106 of first collar102 and second inner collar portion 107 of second collar 103 allowssheath 130 to be coupled to first inner collar portion 106 and secondinner collar portion 107 before first outer collar portion 104 ishermetically coupled to first inner collar portion 106 by fifth weld 136and before second outer collar portion 105 is hermetically coupled tosecond inner collar portion 107 by sixth weld 137.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, sheath 130 is movable relative to first inner collar portion106 of first collar 102 and relative to second inner collar portion 107of second collar 103. The preceding subject matter of this paragraphcharacterizes example 19 of the present disclosure, wherein example 19also includes the subject matter according to example 18, above.

Sheath 130, being movable relative to first inner collar portion 106 offirst collar 102 and relative to second inner collar portion 107 ofsecond collar 103, facilitates compliance of sheath 130 relative tobellows 108 by allowing sheath 130 to move with bellows 108 during useof conduit 100.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, sheath 130 is translatable along central axis 180 relative tofirst inner collar portion 106 of first collar 102 and relative tosecond inner collar portion 107 of second collar 103. The precedingsubject matter of this paragraph characterizes example 20 of the presentdisclosure, wherein example 20 also includes the subject matteraccording to example 19, above.

Sheath 130, being translatable along central axis 180 relative to firstinner collar portion 106 of first collar 102 and relative to secondinner collar portion 107 of second collar 103, accommodates lengthening(e.g., expansion) and shortening (e.g., contraction) of bellows 108during use of conduit 100.

In some examples, sheath 130 is coupled to each of first inner collarportion 106 and second inner collar portion 107 by pins 169 engaged withslots 167 formed in first inner collar portion 106 and second innercollar portion 107. Each one of slots 167 is elongated along centralaxis 180. Each pin 169 passes through a corresponding end of sheath 130and passes into a corresponding one of slots 167. Sheath 130 isnon-movably fixed to pins 169, but each pin 169 is allowed totranslatably move along the corresponding one of slots 167, whichfacilitates translational movement of sheath 130 along central axis 180relative to first inner collar portion 106 and second inner collarportion 107. According to one example, each one of slots 167 has awidth, substantially equal to a width of pins 169, which prevents pins169, and thus sheath 130, from rotating about central axis 180 relativeto first inner collar portion 106 and second inner collar portion 107.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, sheath 130 is rotatable about central axis 180 relative tofirst inner collar portion 106 of first collar 102 and relative tosecond inner collar portion 107 of second collar 103. The precedingsubject matter of this paragraph characterizes example 21 of the presentdisclosure, wherein example 21 also includes the subject matteraccording to example 19 or 20, above.

Sheath 130, being rotatable about central axis 180 relative to firstinner collar portion 106 of first collar 102 and relative to secondinner collar portion 107 of second collar 103, accommodates rotation ofbellows 108 about central axis 180 during use of conduit 100.

In some examples, slots 167 formed in first inner collar portion 106 andsecond inner collar portion 107, are at least partially annular.Accordingly, pins 169, when engaged with slots 167, are allowed to movetranslatably along slots 167 in a circumferential direction relative tofirst inner collar portion 106 and second inner collar portion 107. Suchmovement of pins 169 within slots 167 facilitates rotational movement ofsheath 130 about central axis 180 relative to first inner collar portion106 and second inner collar portion 107. According to one example, eachone of slots 167 has a width that is substantially equal to a width ofeach one of pins 169, which prevents pins 169, and thus sheath 130, fromtranslating along central axis 180 relative to first inner collarportion 106 and second inner collar portion 107. However, in at leastone other example, each one of slots 167 has a width that is greaterthan the width of each one of pins 169. Each one of slots 167, having awidth that is greater than the width of each one of pins 169,accommodates both rotational movement of sheath 130 about central axis180 relative to first inner collar portion 106 and second inner collarportion 107 and translational movement of sheath 130 along central axis180 relative to first inner collar portion 106 and second inner collarportion 107.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, sheath 130 further comprises low-friction layer 189, interposedbetween reinforcement layer 187 of sheath 130 and corrugated outboardply 112 of bellows 108. Low-friction layer 189 of sheath 130 has asurface roughness lower than that of reinforcement layer 187 of sheath130. The preceding subject matter of this paragraph characterizesexample 22 of the present disclosure, wherein example 22 also includesthe subject matter according to any one of examples 17 to 21, above.

Low-friction layer 189 of sheath 130 helps to reduce abrasions betweenreinforcement layer 187 and bellows 108, particularly when bellows 108moves relative to sheath 130.

According to some examples, the surface roughness of low-friction layer189 corresponds with a coefficient-of-friction of the low-friction layer189 between 0.05 and 0.1, and the surface roughness of reinforcementlayer 187 corresponds with a coefficient-of-friction that is higher thanthat of low-friction layer 189. Low-friction layer 189 of sheath 130 ismade of a low-friction material, such as polytetrafluoroethylene,Nylon®, Teflon®, and the like, in some examples. Reinforcement layer 187is made of a high-abrasion-resistance material, such as fiberglass,aramid, stainless steel (mesh), in certain examples.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, low-friction layer 189 of sheath 130 is in contact withcorrugated outboard ply 112 of bellows 108. The preceding subject matterof this paragraph characterizes example 23 of the present disclosure,wherein example 23 also includes the subject matter according to example22, above.

Low-friction layer 189 of sheath 130, being in contact with corrugatedoutboard ply 112, ensures that the outside diameter of sheath 130 is assmall as possible for use in confined spaces.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, bellows 108 further comprises second corrugated outboard ply114. Corrugated outboard ply 112 is interposed between corrugatedinboard ply 110 and second corrugated outboard ply 114. Secondcorrugated outboard ply 114 is hermetically coupled to first innercollar portion 106 by second weld 134 and is hermetically coupled tosecond inner collar portion 107 by fourth weld 184. Low-friction layer189 of sheath 130 is in contact with second corrugated outboard ply 114of bellows 108. The preceding subject matter of this paragraphcharacterizes example 24 of the present disclosure, wherein example 24also includes the subject matter according to example 22 or 23, above.

Low-friction layer 189 of sheath 130, being in contact with secondcorrugated outboard ply 114, ensures that the outside diameter of sheath130 is as small as possible for use in confined spaces.

Referring generally to FIG. 1A and particularly to, e.g., FIGS. 2 and 3,first sensor 116 is configured to detect a pressure change ininterstitial space 126. The preceding subject matter of this paragraphcharacterizes example 25 of the present disclosure, wherein example 25also includes the subject matter according to any one of examples 1 to24, above.

First sensor 116, being configured to detect a pressure change ininterstitial space 126, allows leakage of fluid from corrugated inboardply 110 to be detected. Furthermore, in one or more examples, firstsensor 116, being configured to detect a pressure change in interstitialspace 126, is agnostic to the type of fluid transmitted through conduit100 and leaking from corrugated inboard ply 110, which helps to increasethe versatility of conduit 100.

Referring generally to FIG. 1A and particularly to, e.g., FIGS. 2 and 3,first sensor 116 is configured to detect a chemical change withininterstitial space 126. The preceding subject matter of this paragraphcharacterizes example 26 of the present disclosure, wherein example 26also includes the subject matter according to any one of examples 1 to24, above.

First sensor 116, being configured to detect a change in chemicalcomposition in interstitial space 126, allows leakage of fluid fromcorrugated inboard ply 110 to be detected. Furthermore, in one or moreexamples, first sensor 116, being configured to detect a change inchemical composition in interstitial space 126, is agnostic to thepressure of fluid transmitted through conduit 100 and pressure of fluidin interstitial space 126, which helps to increase the versatility ofconduit 100.

Referring generally to FIGS. 1A and 1C and particularly to, e.g., FIG.12, first sensor 116 comprises first chamber 190, containing firstreactant 198. First sensor 116 further comprises second chamber 192,containing second reactant 199, isolated from first chamber 190, andcommunicatively coupled with interstitial space 126. First reactant 198is identical to second reactant 199. The preceding subject matter ofthis paragraph characterizes example 27 of the present disclosure,wherein example 27 also includes the subject matter according to any oneof examples 1 to 24 and 26, above.

First reactant 198, being the same as second reactant 199, facilitatescontrasting visual conditions if first reactant 198 reacts with gasleaking into interstitial space 126. Because first reactant 198 andsecond reactant 199 are the same, the contrasting visual conditionsoccur despite changes in lighting conditions or discoloration of firstreactant 198 and second reactant 199 due to time or atmosphericconditions. Contrasting visual conditions is enhanced by configuringfirst chamber 190 and second chamber 192 in a side-by-sideconfiguration.

In some examples, first reactant 198 and second reactant 199 ispalladium oxide, which is configured to react (e.g., discolor) in thepresence of hydrogen. First sensor 116 further comprises permeablebarrier 194 and impermeable barrier 196. Second chamber 192 is isolatedfrom first chamber 190 by impermeable barrier 196, which is configuredto prevent passage of first reactant 198 and second reactant 199 intosecond chamber 192 and first chamber 190, respectively, and to preventpassage of fluid into interstitial space 126 from second chamber 192 tofirst chamber 190. Permeable barrier 194 is configured to preventpassage of second reactant 199 from second chamber 192 to first channel118 and interstitial space 126 and to allow passage of fluid, ininterstitial space 126, from interstitial space 126 to second chamber192.

Referring generally to FIG. 1A and particularly to, e.g., FIGS. 2 and 3,conduit 200 for transporting a fluid is disclosed. Conduit 200 comprisesfirst collar 102 that comprises first outer collar portion 104 and firstinner collar portion 106, threadably coupled with first outer collarportion 104. Conduit 200 also comprises bellows 108 that comprisescentral axis 180, corrugated outboard ply 112, corrugated inboard ply110, interposed between corrugated outboard ply 112 and central axis180, and interstitial space 126, interposed between corrugated inboardply 110 and corrugated outboard ply 112. Conduit 200 further comprisesfirst weld 138, hermetically coupling corrugated inboard ply 110 andfirst outer collar portion 104. Conduit 200 additionally comprisessecond weld 134, hermetically coupling corrugated outboard ply 112 andfirst inner collar portion 106. Conduit 200 also comprises first sensor116, communicatively coupled with interstitial space 126. The precedingsubject matter of this paragraph characterizes example 28 of the presentdisclosure.

Conduit 200 provides a compliant structure for transmission of fluids,such as cryogenic fuels, that accommodates displacements encounteredduring operation. First sensor 116, being communicatively coupled withinterstitial space 126, allows first sensor 116 to monitor conditionswithin interstitial space 126. In particular, first sensor 116 enablesdetection of leaks in corrugated inboard ply 110 by detecting changes inconditions within interstitial space 126. First weld 138 promotes astrong, reliable, and sealed connection between corrugated inboard ply110 and first outer collar portion 104. Second weld 134 promotes astrong, reliable, and sealed connection between corrugated outboard ply112 and first inner collar portion 106. Communicatively couplinginterstitial space 126 with first sensor 116 allows leaks of fluid orgas into interstitial space 126 through corrugated inboard ply 110 to bedetected at a location, external to first collar 102.

Referring generally to FIGS. 13A-13E and particularly to, e.g., FIGS.4-12, method 300 of fabricating conduit 100, 200 is disclosed. Method300 comprises (block 202) attaching first tubular-outboard-ply end 149of tubular outboard ply 113 to first inner collar portion 106 of firstcollar 102 with second weld 134. Method 300 also comprises (block 204)attaching second tubular-outboard-ply end 147 of tubular outboard ply113, which is axially opposite first tubular-outboard-ply end 149 oftubular outboard ply 113, to second inner collar portion 107 of secondcollar 103 with fourth weld 184. Method 300 further comprises (block206) inserting tubular inboard ply 111 into tubular outboard ply 113 andadvancing tubular inboard ply 111 along an interior of tubular outboardply 113 until first tubular-inboard-ply end 157 of tubular inboard ply111 protrudes first distance D1 past first inner collar portion 106, andsecond tubular-inboard-ply end 159 protrudes second distance D2 pastsecond inner collar portion 107. First distance D1 is greater than firstpredetermined distance PD1 and second distance D2 is greater than secondpredetermined distance PD1. Method 300 additionally comprises (block208) simultaneously corrugating tubular inboard ply 111 and tubularoutboard ply 113 to form bellows 108, having central axis 180 andcomprising corrugated outboard ply 112, corrugated inboard ply 110, andinterstitial space 126, interposed between corrugated inboard ply 110and corrugated outboard ply 112. Corrugated outboard ply 112 is formedfrom tubular outboard ply 113, and corrugated inboard ply 110 is formedfrom tubular inboard ply 111. Method 300 also comprises (block 210)trimming first corrugated-inboard-ply end 151 of corrugated inboard ply110, corresponding to first tubular-inboard-ply end 157 of tubularinboard ply 111, to create trimmed first corrugated-inboard-ply end 156that protrudes first predetermined distance PD1 past first inner collarportion 106. Method 300 further comprises (block 212) trimming secondcorrugated-inboard-ply end 153 of corrugated inboard ply 110,corresponding to second tubular-inboard-ply end 159 of tubular inboardply 111, to create trimmed second corrugated-inboard-ply end 170 thatprotrudes second predetermined distance PD2 past second inner collarportion 107. Method 300 additionally comprises (block 214) threadablyinterconnecting first inner collar portion 106 and first outer collarportion 104 of first collar 102. Method 300 also comprises (block 216)threadably interconnecting second inner collar portion 107 and secondouter collar portion 105 of second collar 103. Method 300 furthercomprises (block 218) attaching trimmed first corrugated-inboard-ply end156 of corrugated inboard ply 110 to first outer collar portion 104 withfirst weld 138. Method 300 additionally comprises (block 220) attachingtrimmed second corrugated-inboard-ply end 170 of corrugated inboard ply110 to second outer collar portion 105 with third weld 186. Method 300also comprises (block 222) communicatively coupling first sensor 116with interstitial space 126. The preceding subject matter of thisparagraph characterizes example 29 of the present disclosure.

Method 300 facilitates fabrication of conduit 100 in an efficient andsimple manner. Conduit 100 provides a compliant structure fortransmission of fluids, such as cryogenic fuels, that accommodatesdisplacements encountered during operation. First sensor 116, beingcommunicatively coupled with interstitial space 126, allows first sensor116 to monitor conditions within interstitial space 126. The threadableinterconnection between first outer collar portion 104 and first innercollar portion 106 facilitates hermetical coupling of first outer collarportion 104 and first inner collar portion 106 while allowing firstouter collar portion 104 to be separately formed from and interconnectedto first inner collar portion 106, which enables bellows 108 to behermetically coupled to first collar 102 in a simple and efficientmanner. Similarly, the threadable interconnection between second outercollar portion 105 and second inner collar portion 107 facilitateshermetical coupling of second outer collar portion 105 and second innercollar portion 107 while allowing second outer collar portion 105 to beseparately formed from and interconnected to second inner collar portion107, which enables bellows 108 to be hermetically coupled to secondcollar 103 in a simple and efficient manner. First weld 138 promotes astrong, reliable, and sealed connection between corrugated inboard ply110 and first outer collar portion 104. Second weld 134 promotes astrong, reliable, and sealed connection between corrugated outboard ply112 and first inner collar portion 106. Third weld 186 promotes astrong, reliable, and sealed connection between corrugated inboard ply110 and second outer collar portion 105. Fourth weld 184 promotes astrong, reliable, and sealed connection between corrugated outboard ply112 and second inner collar portion 107. Advancing tubular inboard ply111 along an interior of tubular outboard ply 113 until firsttubular-inboard-ply end 157 of tubular inboard ply 111 protrudes firstdistance D1 past first inner collar portion 106, and secondtubular-inboard-ply end 159 protrudes second distance D2 past secondinner collar portion 107 accommodates the reduction in the length oftubular inboard ply 111 after tubular inboard ply 111 is corrugated.Simultaneously corrugating tubular outboard ply 113 and tubular inboardply 111 to form bellows 108 promotes corrugations 158 in corrugatedinboard ply 110 and corrugated outboard ply 112 of bellows 108 that arecomplementary to each other. Trimming first corrugated-inboard-ply end151 of corrugated inboard ply 110 and trimming secondcorrugated-inboard-ply end 153 of corrugated inboard ply 110 promotesachieving a desired length of corrugated inboard ply 110 aftercorrugation of tubular inboard ply 111. Communicatively couplinginterstitial space 126 with first sensor 116 allows leaks of fluid orgas into interstitial space 126 through corrugated inboard ply 110 to bedetected at a location, external to first collar 102 and second collar103.

After corrugating tubular outboard ply 113, first tubular-outboard-plyend 149 of tubular outboard ply 113 becomes firstcorrugated-outboard-ply end 146 of corrugated outboard ply 112 andsecond tubular-outboard-ply end 147 of tubular outboard ply 113 becomessecond corrugated-outboard-ply end 171 of corrugated outboard ply 112.

Referring generally to FIG. 13A and particularly to, e.g., FIG. 6,according to method 300, (block 206) inserting tubular inboard ply 111into tubular outboard ply 113 comprises (block 246) inserting firsttubular-inboard-ply end 157 of tubular inboard ply 111 into secondtubular-outboard-ply end 147 of tubular outboard ply 113. The precedingsubject matter of this paragraph characterizes example 30 of the presentdisclosure, wherein example 30 also includes the subject matteraccording to example 29, above.

Inserting first tubular-inboard-ply end 157 of tubular inboard ply 111into second tubular-outboard-ply end 147 of tubular outboard ply 113allows first tubular-inboard-ply end 157 to be positioned first distanceD1 past first inner collar portion 106 in an efficient manner.

Referring generally to FIGS. 13B and 13C and particularly to, e.g.,FIGS. 6-8 and 11, according to method 300, (block 250) first innercollar portion 106 is threadably coupled with first outer collar portion104 and (block 258) second inner collar portion 107 is threadablycoupled with second outer collar portion 105 after tubular inboard ply111 is advanced along interior of tubular outboard ply 113 and aftertubular inboard ply 111 and tubular outboard ply 113 are simultaneouslycorrugated. The preceding subject matter of this paragraph characterizesexample 31 of the present disclosure, wherein example 31 also includesthe subject matter according to example 29 or 30, above.

Threadably interconnecting first inner collar portion 106 with firstouter collar portion 104 and threadably interconnecting second innercollar portion 107 with second outer collar portion 105, after tubularinboard ply 111 is advanced along interior of tubular outboard ply 113and after tubular inboard ply 111 and tubular outboard ply 113 aresimultaneously corrugated, promotes ease in trimming firstcorrugated-inboard-ply end 151 and second corrugated-inboard-ply end 153to create trimmed first corrugated-inboard-ply end 156 and trimmedsecond corrugated-inboard-ply end 170, as it is possible to positionfirst outer collar portion 104 and second outer collar portion 105 awayfrom and out of the way of first inner collar portion 106 and secondinner collar portion 107 during the trimming operations.

Referring generally to FIG. 13A and particularly to, e.g., FIGS. 5-7,according to method 300, (block 248) tubular inboard ply 111 is insertedinto tubular outboard ply 113 after first tubular-outboard-ply end 149of tubular outboard ply 113 is attached to first inner collar portion106 and after second tubular-outboard-ply end 147 of tubular outboardply 113 is attached to second inner collar portion 107. The precedingsubject matter of this paragraph characterizes example 32 of the presentdisclosure, wherein example 32 also includes the subject matteraccording to example 31, above.

Inserting tubular inboard ply 111 into tubular outboard ply 113 afterfirst tubular-outboard-ply end 149 of tubular outboard ply 113 isattached to first inner collar portion 106 and after secondtubular-outboard-ply end 147 of tubular outboard ply 113 is attached tosecond inner collar portion 107 promotes ease in welding firsttubular-outboard-ply end 149 to first inner collar portion 106 andwelding second tubular-outboard-ply end 147 to second inner collarportion 107 by reducing obstructions to the welding site.

Referring generally to FIGS. 13C and 13D and particularly to, e.g.,FIGS. 11 and 12, according to method 300, (block 266) trimmed firstcorrugated-inboard-ply end 156 of corrugated inboard ply 110 is attachedto first outer collar portion 104 after first inner collar portion 106and first outer collar portion 104 are threadably interconnected.Trimmed second corrugated-inboard-ply end 170 of corrugated inboard ply110 is attached to second outer collar portion 105 after second innercollar portion 107 and second outer collar portion 105 are threadablyinterconnected. The preceding subject matter of this paragraphcharacterizes example 33 of the present disclosure, wherein example 33also includes the subject matter according to example 32, above.

Attaching trimmed first corrugated-inboard-ply end 156 of corrugatedinboard ply 110 to first outer collar portion 104 after first innercollar portion 106 and first outer collar portion 104 are threadablyinterconnected, and attaching trimmed second corrugated-inboard-ply end170 of corrugated inboard ply 110 to second outer collar portion 105after second inner collar portion 107 and second outer collar portion105 are threadably interconnected allows first outer collar portion 104and second outer collar portion 105 to be properly positioned to receivetrimmed first corrugated-inboard-ply end 156 and trimmed secondcorrugated-inboard-ply end 170, respectively.

Referring generally to FIG. 13D and particularly to, e.g., FIGS. 2, 3,and 12, according to method 300, first sensor 116 is communicativelycoupled with interstitial space 126 via first channel 118, passingthrough one of first inner collar portion 106 or first outer collarportion 104. First channel 118 is cross-sectionally circumferentiallyclosed. The preceding subject matter of this paragraph characterizesexample 34 of the present disclosure, wherein example 34 also includesthe subject matter according to any one of examples 29 to 33, above.

Communicatively coupling interstitial space 126 with first sensor 116,via first channel 118 passing through one of first outer collar portion104 or first inner collar portion 106, allows leaks of fluid or gas intointerstitial space 126 through corrugated inboard ply 110 to be detectedat any of various locations external to first collar 102, which helps tosimplify the assembly and design of first collar 102 of conduit 100.

Referring generally to FIG. 13D and particularly to, e.g., FIG. 3,method 300 further comprises (block 224) communicatively coupling secondsensor 117 with interstitial space 126 via second channel 119, passingthrough one of second inner collar portion 107 or second outer collarportion 105. Second channel 119 is cross-sectionally circumferentiallyclosed. The preceding subject matter of this paragraph characterizesexample 35 of the present disclosure, wherein example 35 also includesthe subject matter according to example 34, above.

Communicatively coupling interstitial space 126 with second sensor 117,via second channel 119 passing through one of second outer collarportion 105 or second inner collar portion 107, allows leaks of fluid orgas into interstitial space 126 through corrugated inboard ply 110 to bedetected at any of various locations external to second collar 103,which helps to simplify the assembly and design of second collar 103 ofconduit 100. Additionally, second sensor 117, being communicativelycoupled with interstitial space 126 along with first sensor 116,promotes redundant detection of leakage through corrugated inboard ply110. In one or more examples, second sensor 117 is able to detect achange in pressure or chemical composition in interstitial space 126that is not detectable by first sensor 116 for various reasons, such as,for example, when fluid, leaking through corrugated inboard ply 110,does not reach first sensor 116 or when first sensor 116 is disabled.

Referring generally to FIG. 13D and particularly to, e.g., FIG. 12,method 300 further comprises (block 226) reducing pressure ininterstitial space 126 to below atmospheric pressure after first sensor116 is communicatively coupled with interstitial space 126. Thepreceding subject matter of this paragraph characterizes example 36 ofthe present disclosure, wherein example 36 also includes the subjectmatter according to any one of examples 29 to 35, above.

Reducing pressure in interstitial space 126 to below atmosphericpressure ensures pressure in interstitial space 126 is not excessivewhen conduit 100 is used in space.

Referring generally to FIG. 13D and particularly to, e.g., FIG. 12,according to method 300, (block 288) pressure in interstitial space 126is reduced by creating a pressure gradient across vacuum port 120,communicatively coupled with interstitial space 126. The precedingsubject matter of this paragraph characterizes example 37 of the presentdisclosure, wherein example 37 also includes the subject matteraccording to example 36, above.

Vacuum port 120 enables pressure in interstitial space 126 to be reducedfrom location external to first collar 102 after first sensor 116 iscommunicatively coupled with interstitial space 126. Pressure gradientacross vacuum port 120 is created by communicatively coupling pump 197to vacuum port 120.

Referring generally to FIG. 13D and particularly to, e.g., FIGS. 2, 3,and 12, method 300 further comprises (block 228) sealing vacuum port120, after pressure in interstitial space 126 is reduced, by closingpinch-off tube 140. The preceding subject matter of this paragraphcharacterizes example 38 of the present disclosure, wherein example 38also includes the subject matter according to example 37, above.

Pinch-off tube 140 provides quick and easy sealing of vacuum port 120after pressure is reduced. Pump 197 is communicatively coupled to vacuumport 120 by pinch-off tube 140.

In some examples, pinch-off tube 140 has a sufficient length that isconducive to multiple pressure-reduction and closing operations.

Referring generally to FIGS. 13A and 13D and particularly to, e.g.,FIGS. 4 and 5, method 300 further comprises (block 230) flaring firsttubular-outboard-ply end 149 of tubular outboard ply 113 to create firstflared portion 148 of first tubular-outboard-ply end 149. According tomethod 300, (block 202) attaching first tubular-outboard-ply end 149 oftubular outboard ply 113 to first inner collar portion 106 comprises(block 242) attaching first flared portion 148 of firsttubular-outboard-ply end 149 to first beveled weld-joint recess 144 offirst inner collar portion 106 with second weld 134. Method 300 alsocomprises (block 232) flaring second tubular-outboard-ply end 147 oftubular outboard ply 113 to create second flared portion 181 of secondtubular-outboard-ply end 147. According to method 300, (block 204)attaching second tubular-outboard-ply end 147 of tubular outboard ply113 to second inner collar portion 107 comprises (block 244) attachingsecond flared portion 181 of second tubular-outboard-ply end 147 tosecond beveled weld-joint recess 161 of second inner collar portion 107with fourth weld 184. The preceding subject matter of this paragraphcharacterizes example 39 of the present disclosure, wherein example 39also includes the subject matter according to any one of examples 29 to38, above.

Flaring first tubular-outboard-ply end 149 of tubular outboard ply 113to create first flared portion 148 of first tubular-outboard-ply end 149and attaching first flared portion 148 of first tubular-outboard-ply end149 to first beveled weld-joint recess 144 of first inner collar portion106 with second weld 134 helps to weld first tubular-outboard-ply end149 to first inner collar portion 106 without second weld 134obstructing interstitial space 126 or obstructing insertion of tubularinboard ply 111 into tubular outboard ply 113. Flaring secondtubular-outboard-ply end 147 of tubular outboard ply 113 to createsecond flared portion 181 of second tubular-outboard-ply end 147 andattaching second flared portion 181 of second tubular-outboard-ply end147 to second beveled weld-joint recess 161 of second inner collarportion 107 with fourth weld 184 helps to weld secondtubular-outboard-ply end 147 to second inner collar portion 107 withoutfourth weld 184 obstructing interstitial space 126 or obstructinginsertion of tubular inboard ply 111 into tubular outboard ply 113.

Referring generally to FIG. 13E and particularly to, e.g., FIGS. 5 and8, method 300 further comprises (block 234) attaching firstsecond-tubular-outboard-ply end 174 of second tubular outboard ply 115to first inner collar portion 106 with second weld 134. Method 300 alsocomprises (block 236) attaching second second-tubular-outboard-ply end176 of second tubular outboard ply 115, which is axially opposite firstsecond-tubular-outboard-ply end 174 of second tubular outboard ply 115,to second inner collar portion 107 of second collar 103 with fourth weld184. Method 300 additionally comprises (block 238) corrugating secondtubular outboard ply 115 simultaneously with tubular inboard ply 111 andtubular outboard ply 113 to form bellows 108, which further comprisessecond corrugated outboard ply 114. Tubular outboard ply 113 isinterposed between tubular inboard ply 111 and second tubular outboardply 115. Second corrugated outboard ply 114 is formed from secondtubular outboard ply 115. The preceding subject matter of this paragraphcharacterizes example 40 of the present disclosure, wherein example 40also includes the subject matter according to any one of examples 29 to39, above.

Second corrugated outboard ply 114 provides a redundant outboard ply,which promotes fault tolerance of conduit 100 by enabling conduit 100 tocontinue to operate if corrugated outboard ply 112 fails. Additionally,second corrugated outboard ply 114 protects corrugated outboard ply 112from abrasions caused by objects outboard of corrugated outboard ply112, such as sheath 130.

After corrugating second tubular outboard ply 115, firstsecond-tubular-outboard-ply end 174 of second tubular outboard ply 115becomes first second-corrugated-outboard-ply end 172 of secondcorrugated outboard ply 114 and second second-tubular-outboard-ply end176 of second tubular outboard ply 115 becomes secondsecond-corrugated-outboard-ply end 177 of second corrugated outboard ply114.

In one or more examples, method 300 also comprises flaring firstsecond-tubular-outboard-ply end 174 of second tubular outboard ply 115to create third flared portion 178 of first second-tubular-outboard-plyend 174. Attaching first second-tubular-outboard-ply end 174 of secondtubular outboard ply 115 to first inner collar portion 106 comprisesattaching third flared portion 178 to first beveled weld-joint recess144 with second weld 134. Method 300 additionally comprises flaringsecond second-tubular-outboard-ply end 176 of second tubular outboardply 115 to create fourth flared portion 182 of second tubular outboardply 115. Attaching second second-tubular-outboard-ply end 176 of secondtubular outboard ply 115 to second inner collar portion 107 comprisesattaching fourth flared portion 182 to second beveled weld-joint recess161 with fourth weld 184.

Referring generally to FIG. 13E and particularly to, e.g., FIG. 4,method 300 further comprises one of (block 290) selecting tubularoutboard ply 113 and second tubular outboard ply 115 to have equallengths, or (block 292) trimming at least one of tubular outboard ply113 or second tubular outboard ply 115 so that tubular outboard ply 113and second tubular outboard ply 115 have equal lengths. The precedingsubject matter of this paragraph characterizes example 41 of the presentdisclosure, wherein example 41 also includes the subject matteraccording to example 40, above.

Tubular outboard ply 113 and second tubular outboard ply 115, havingequal lengths, enables tubular outboard ply 113 and second tubularoutboard ply 115 to be attached to first collar 102 by a single weld andenables tubular outboard ply 113 and second tubular outboard ply 115 tobe attached to second collar 103 by a single weld.

Referring generally to FIGS. 13D and 13E and particularly to, e.g.,FIGS. 4 and 5, method 300 further comprises (block 292) flaring firstsecond-tubular-outboard-ply end 174 of second tubular outboard ply 115to create third flared portion 178 of first second-tubular-outboard-plyend 174. According to method 300, (block 234) attaching firstsecond-tubular-outboard-ply end 174 of second tubular outboard ply 115to first inner collar portion 106 comprises (block 287) attaching thirdflared portion 178 of first second-tubular-outboard-ply end 174 to firstbeveled weld-joint recess 144 of first inner collar portion 106 withsecond weld 134. Method 300 also comprises (block 294) flaring secondsecond-tubular-outboard-ply end 176 of second tubular outboard ply 115to create fourth flared portion 182 of secondsecond-tubular-outboard-ply end 176. According to method 300, (block236) attaching second second-tubular-outboard-ply end 176 of secondtubular outboard ply 115 to second inner collar portion 107 comprises(block 289) attaching fourth flared portion 182 of secondsecond-tubular-outboard-ply end 176 to second beveled weld-joint recess161 of second inner collar portion 107 with fourth weld 184. Thepreceding subject matter of this paragraph characterizes example 42 ofthe present disclosure, wherein example 42 also includes the subjectmatter according to example 40 or 41, above.

Flaring first second tubular-outboard-ply end 174 of second tubularoutboard ply 115 to create third flared portion 178 of firstsecond-tubular-outboard-ply end 174 and attaching third flared portion178 of first second-tubular-outboard-ply end 174 to first beveledweld-joint recess 144 of first inner collar portion 106 with second weld134 helps to weld first second-tubular-outboard-ply end 174 to firstinner collar portion 106 without second weld 134 obstructinginterstitial space 126 or obstructing insertion of tubular inboard ply111 into tubular outboard ply 113. Flaring secondsecond-tubular-outboard-ply end 176 of second tubular outboard ply 115to create fourth flared portion 182 of secondsecond-tubular-outboard-ply end 176 and attaching fourth flared portion182 of second second-tubular-outboard-ply end 176 to second beveledweld-joint recess 161 of second inner collar portion 107 with fourthweld 184 helps to weld second second-tubular-outboard-ply end 176 tosecond inner collar portion 107 without fourth weld 184 obstructinginterstitial space 126 or obstructing insertion of tubular inboard ply111 into tubular outboard ply 113.

Referring generally to FIGS. 13C and 13D and particularly to, e.g.,FIGS. 10-12, according to method 300, first outer collar portion 104 offirst collar 102 comprises first annular weld-joint recess 145. Secondouter collar portion 105 of second collar 103 comprises second annularweld-joint recess 163. Trimmed first corrugated-inboard-ply end 156 ofcorrugated inboard ply 110 is attached to first annular weld-jointrecess 145 of first outer collar portion 104 by first weld 138. Trimmedsecond corrugated-inboard-ply end 170 of corrugated inboard ply 110 isattached to second annular weld-joint recess 163 of second outer collarportion 105 by third weld 186 third weld 186. The preceding subjectmatter of this paragraph characterizes example 43 of the presentdisclosure, wherein example 43 also includes the subject matteraccording to any one of examples 29 to 42, above.

First annular weld-joint recess 145 helps to receive, retain, and aligntrimmed first corrugated-inboard-ply end 156 of corrugated inboard ply110 for welding to first outer collar portion 104. Similarly, secondannular weld-joint recess 163 helps to receive, retain, and aligntrimmed second corrugated-inboard-ply end 170 of corrugated inboard ply110 for welding to second outer collar portion 105.

Referring generally to FIGS. 13B and 13C and particularly to, e.g.,FIGS. 2, 3, and 10-12, according to method 300, (block 214) threadablyinterconnecting first inner collar portion 106 and first outer collarportion 104 of first collar 102 comprises (block 296) threadablyengaging first threads 152 of first outer collar portion 104 with secondthreads 154 of first inner collar portion 106 so that first abutmentinterface 139 is formed between first outer collar portion 104 and firstinner collar portion 106. According to method 300, (block 216)threadably interconnecting second inner collar portion 107 and secondouter collar portion 105 of second collar 103 comprises (block 298)threadably engaging third threads 142 of second outer collar portion 105with fourth threads 143 of second inner collar portion 107 so thatsecond abutment interface 141 is formed between second outer collarportion 105 and second inner collar portion 107. The preceding subjectmatter of this paragraph characterizes example 44 of the presentdisclosure, wherein example 44 also includes the subject matteraccording to any one of examples 29 to 43, above.

Threadable engagement between first threads 152 and second threads 154enables first outer collar portion 104 to be coupled to first innercollar portion 106 in a simple and efficient manner. Similarly,threadable engagement between third threads 142 and fourth threads 143enables second outer collar portion 105 to be coupled to second innercollar portion 107 in a simple and efficient manner. First abutmentinterface 139 and second abutment interface 141 promote hermeticalcoupling of first outer collar portion 104 and first inner collarportion 106, and second outer collar portion 105 and second inner collarportion 107, respectively, at locations away from first threads 152 andsecond threads 154 and away from third threads 142 and fourth threads143, which allows hermetical sealing of first outer collar portion 104and first inner collar portion 106, and second outer collar portion 105and second inner collar portion 107, to be performed separately fromthreadably engagement between first outer collar portion 104 and firstinner collar portion 106, and second outer collar portion 105 and secondinner collar portion 107.

Referring generally to FIG. 13C and particularly to, e.g., FIGS. 2, 3,11, and 12, method 300 further comprises (block 280) hermeticallysealing first abutment interface 139 between first outer collar portion104 and first inner collar portion 106 with fifth weld 136. Method 300additionally comprises (block 282) hermetically sealing second abutmentinterface 141 between second outer collar portion 105 and second innercollar portion 107 with sixth weld 137. The preceding subject matter ofthis paragraph characterizes example 45 of the present disclosure,wherein example 45 also includes the subject matter according to example44, above.

Fifth weld 136 enables hermetical coupling of first outer collar portion104 and first inner collar portion 106. Similarly, sixth weld 137enables hermetical coupling of second outer collar portion 105 andsecond inner collar portion 107. First threads 152 and second threads154 enable a strong mechanical coupling of first outer collar portion104 and first inner collar portion 106, which allows fifth weld 136 tobe configured primarily for hermetical coupling of first outer collarportion 104 and first inner collar portion 106. Accordingly, in one ormore examples, fifth weld 136 is relatively smaller, or be of adifferent type of weld, than a weld for providing the sole mechanicalcoupling of first outer collar portion 104 and first inner collarportion 106. Third threads 142 and fourth threads 143 enable a strongmechanical coupling of plies to second outer collar portion 105 andsecond inner collar portion 107, which allows sixth weld 137 to beconfigured primarily for hermetical coupling of second outer collarportion 105 and second inner collar portion 107. Accordingly, in one ormore examples, sixth weld 137 is relatively smaller, or be of adifferent type of weld, than a weld for providing the sole mechanicalcoupling of second outer collar portion 105 and second inner collarportion 107.

Referring generally to FIGS. 13B and 13C and particularly to, e.g.,FIGS. 2 and 3, method 300 further comprises coupling sheath 130 to firstinner collar portion 106 of first collar 102 and second inner collarportion 107 of second collar 103 before first abutment interface 139 ishermetically sealed with fifth weld 136 and before second abutmentinterface 141 is hermetically sealed with sixth weld 137. Corrugatedoutboard ply 112 is interposed between sheath 130 and central axis 180of bellows 108. The preceding subject matter of this paragraphcharacterizes example 46 of the present disclosure, wherein example 46also includes the subject matter according to example 45, above.

Sheath 130 helps to protect bellows 108 from external objects. Sheath130 is slid over one of first inner collar portion 106 or second innercollar portion 107 into a position for coupling to first inner collarportion 106 and second inner collar portion 107. Coupling sheath 130 tofirst inner collar portion 106 of first collar 102 and second innercollar portion 107 of second collar 103 before first abutment interface139 is hermetically sealed with fifth weld 136 and before secondabutment interface 141 is hermetically sealed with sixth weld 137enables sheath 130 to be positioned for coupling to first inner collarportion 106 and second inner collar portion 107 before fifth weld 136and sixth weld 137 obstruct slidable access of sheath 130 to first innercollar portion 106 and second inner collar portion 107.

Referring generally to FIGS. 13C and 13D and particularly to, e.g.,FIGS. 2 and 3, according to method 300, first weld 138 is offset fromsecond weld 134 along central axis 180 of bellows 108. Third weld 186 isoffset from fourth weld 184 along central axis 180 of bellows 108. Thepreceding subject matter of this paragraph characterizes example 47 ofthe present disclosure, wherein example 47 also includes the subjectmatter according to any one of examples 29 to 46, above.

First weld 138, being offset from second weld 134 along central axis 180of bellows 108, helps to ensure first sensor 116 remains communicativelycoupled with interstitial space 126 by ensuring first weld 138 is clearof second weld 134 in axial direction along central axis 180. Third weld186, being offset from fourth weld 184 along central axis 180 of bellows108, helps to ensure interstitial space 126 is open to second cavity 125by ensuring third weld 186 is clear of fourth weld 184 in axialdirection along central axis 180.

Referring generally to FIGS. 13C and 13D and particularly to, e.g.,FIGS. 2 and 3, according to method 300, first weld 138 is offset fromsecond weld 134 along an axis, perpendicular to central axis 180 ofbellows 108, and is closer to central axis 180 than second weld 134.According to method 300, third weld 186 is offset from fourth weld 184along an axis, perpendicular to central axis 180 of bellows 108, and iscloser to central axis 180 than fourth weld 184. The preceding subjectmatter of this paragraph characterizes example 48 of the presentdisclosure, wherein example 48 also includes the subject matteraccording to any one of examples 29 to 47, above.

First weld 138, being offset from second weld 134 along an axis,perpendicular to central axis 180 of bellows 108, and being closer tocentral axis 180 than second weld 134 helps to ensure first sensor 116remains communicatively coupled with interstitial space 126 by ensuringfirst weld 138 is clear of second weld 134 in radial direction relativeto central axis 180. Third weld 186, being offset from fourth weld 184along an axis, perpendicular to central axis 180 of bellows 108, andbeing closer to central axis 180 than fourth weld 184 helps to ensureinterstitial space 126 is open to second cavity 125 by ensuring thirdweld 186 is clear of fourth weld 184 in radial direction relative tocentral axis 180.

Examples of the present disclosure may be described in the context ofaircraft manufacturing and service method 1100 as shown in FIG. 14 andaircraft 1102 as shown in FIG. 15. During pre-production, illustrativemethod 1100 may include specification and design (block 1104) ofaircraft 1102 and material procurement (block 1106). During production,component and subassembly manufacturing (block 1108) and systemintegration (block 1110) of aircraft 1102 may take place. Thereafter,aircraft 1102 may go through certification and delivery (block 1112) tobe placed in service (block 1114). While in service, aircraft 1102 maybe scheduled for routine maintenance and service (block 1116). Routinemaintenance and service may include modification, reconfiguration,refurbishment, etc. of one or more systems of aircraft 1102.

Each of the processes of illustrative method 1100 may be performed orcarried out by a system integrator, a third party, and/or an operator(e.g., a customer). For the purposes of this description, a systemintegrator may include, without limitation, any number of aircraftmanufacturers and major-system subcontractors; a third party mayinclude, without limitation, any number of vendors, subcontractors, andsuppliers; and an operator may be an airline, leasing company, militaryentity, service organization, and so on.

As shown in FIG. 15, aircraft 1102 produced by illustrative method 1100may include airframe 1118 with a plurality of high-level systems 1120and interior 1122. Examples of high-level systems 1120 include one ormore of propulsion system 1124, electrical system 1126, hydraulic system1128, and environmental system 1130. Any number of other systems may beincluded. Although an aerospace example is shown, the principlesdisclosed herein may be applied to other industries, such as theautomotive industry. Accordingly, in addition to aircraft 1102, theprinciples disclosed herein may apply to other vehicles, e.g., landvehicles, marine vehicles, space vehicles, etc.

Apparatus(es) and method(s) shown or described herein may be employedduring any one or more of the stages of the manufacturing and servicemethod 1100. For example, components or subassemblies corresponding tocomponent and subassembly manufacturing (block 1108) may be fabricatedor manufactured in a manner similar to components or subassembliesproduced while aircraft 1102 is in service (block 1114). Also, one ormore examples of the apparatus(es), method(s), or combination thereofmay be utilized during production stages 1108 and 1110, for example, bysubstantially expediting assembly of or reducing the cost of aircraft1102. Similarly, one or more examples of the apparatus or methodrealizations, or a combination thereof, may be utilized, for example andwithout limitation, while aircraft 1102 is in service (block 1114)and/or during maintenance and service (block 1116).

Different examples of the apparatus(es) and method(s) disclosed hereininclude a variety of components, features, and functionalities. Itshould be understood that the various examples of the apparatus(es) andmethod(s) disclosed herein may include any of the components, features,and functionalities of any of the other examples of the apparatus(es)and method(s) disclosed herein in any combination, and all of suchpossibilities are intended to be within the scope of the presentdisclosure.

Many modifications of examples set forth herein will come to mind to oneskilled in the art to which the present disclosure pertains having thebenefit of the teachings presented in the foregoing descriptions and theassociated drawings.

Therefore, it is to be understood that the present disclosure is not tobe limited to the specific examples illustrated and that modificationsand other examples are intended to be included within the scope of theappended claims. Moreover, although the foregoing description and theassociated drawings describe examples of the present disclosure in thecontext of certain illustrative combinations of elements and/orfunctions, it should be appreciated that different combinations ofelements and/or functions may be provided by alternative implementationswithout departing from the scope of the appended claims. Accordingly,parenthetical reference numerals in the appended claims are presentedfor illustrative purposes only and are not intended to limit the scopeof the claimed subject matter to the specific examples provided in thepresent disclosure.

1. A conduit (100) for transporting a fluid, the conduit (100)comprising: a first collar (102) that comprises: a first outer collarportion (104); and a first inner collar portion (106), threadablycoupled with the first outer collar portion (104); a second collar (103)that comprises: a second outer collar portion (105); and a second innercollar portion (107), threadably coupled with the second outer collarportion (105); a bellows (108) that comprises: a central axis (180); acorrugated outboard ply (112); a corrugated inboard ply (110),interposed between the corrugated outboard ply (112) and the centralaxis (180); and an interstitial space (126), interposed between thecorrugated inboard ply (110) and the corrugated outboard ply (112); afirst weld (138), hermetically coupling the corrugated inboard ply (110)and the first outer collar portion (104); a second weld (134),hermetically coupling the corrugated outboard ply (112) and the firstinner collar portion (106); a third weld (186), hermetically couplingthe corrugated inboard ply (110) and the second outer collar portion(105); a fourth weld (184), hermetically coupling the corrugatedoutboard ply (112) and the second inner collar portion (107); and afirst sensor (116), communicatively coupled with the interstitial space(126).
 2. (canceled)
 3. The conduit (100) according to claim 1, wherein:the first collar (102) further comprises a first channel (118), passingthrough one of the first outer collar portion (104) or the first innercollar portion (106); the first channel (118) is cross-sectionallycircumferentially closed; the first channel (118) is communicativelycoupled with the interstitial space (126) of the bellows (108); and thefirst sensor (116) is communicatively coupled with the first channel(118) of the first collar (102). 4-6. (canceled)
 5. The conduit (100)according to claim 3, wherein pressure in the interstitial space (126)and in the first channel (118) is no more than 15 pounds per square inch(psi).
 6. The conduit (100) according to claim 5, wherein the pressurein the interstitial space (126) and in the first channel (118) is nomore than 5 psi.
 7. The conduit (100) according to claim 3, wherein: thefirst collar (102) further comprises a first cavity (124), locatedbetween the first outer collar portion (104) and the first inner collarportion (106); the second collar (103) further comprises a second cavity(125), located between the second outer collar portion (105) and thesecond inner collar portion (107); the first channel (118) iscommunicatively coupled with the first cavity (124); the first cavity(124) has an annular shape and is communicatively coupled with theinterstitial space (126); and the second cavity (125) has an annularshape and is communicatively coupled with the interstitial space (126).8. The conduit (100) according to claim 7, further comprising a secondsensor (117), and wherein: the second collar (103) further comprises asecond channel (119), passing through one of the second outer collarportion (105) or the second inner collar portion (107); the secondchannel (119) is cross-sectionally circumferentially closed; the secondchannel (119) is communicatively coupled with the interstitial space(126) of the bellows (108); and the second sensor (117) iscommunicatively coupled with the second channel (119) of the secondcollar (103). 9-11. (canceled)
 12. The conduit (100) according to claim1, wherein: the bellows (108) further comprises a second corrugatedoutboard ply (114); the corrugated outboard ply (112) is interposedbetween the corrugated inboard ply (110) and the second corrugatedoutboard ply (114); and the second corrugated outboard ply (114) ishermetically coupled to the first inner collar portion (106) by thesecond weld (134) and is hermetically coupled to the second inner collarportion (107) by the fourth weld (184). 13-14. (canceled)
 15. Theconduit (100) according to claim 1, wherein: the first outer collarportion (104) comprises first threads (152); the first inner collarportion (106) comprises second threads (154), threadably engaged withthe first threads (152) of the first outer collar portion (104) so thata first abutment interface (139) is formed between the first outercollar portion (104) and the first inner collar portion (106); thesecond outer collar portion (105) comprises third threads (142); and thesecond inner collar portion (107) comprises fourth threads (143),threadably engaged with the third threads (142) of the second outercollar portion (105) so that a second abutment interface (141) is formedbetween the second outer collar portion (105) and the second innercollar portion (107).
 16. The conduit (100) according to claim 15,wherein: the first collar (102) further comprises a fifth weld (136),hermetically coupling the first outer collar portion (104) and the firstinner collar portion (106) along the first abutment interface (139)between the first outer collar portion (104) and the first inner collarportion (106); and the second collar (103) further comprises a sixthweld (137), hermetically coupling the second outer collar portion (105)and the second inner collar portion (107) along the second abutmentinterface (141) between the second outer collar portion (105) and thesecond inner collar portion (107).
 17. The conduit (100) according toclaim 1, further comprising a sheath (130) that comprises areinforcement layer (187), and wherein the corrugated outboard ply (112)is interposed between the sheath (130) and the central axis (180). 18.The conduit (100) according to claim 17, wherein the sheath (130) iscoupled to the first inner collar portion (106) of the first collar(102) and to the second inner collar portion (107) of the second collar(103).
 19. The conduit (100) according to claim 18, wherein the sheath(130) is movable relative to the first inner collar portion (106) of thefirst collar (102) and relative to the second inner collar portion (107)of the second collar (103). 20-21. (canceled)
 22. The conduit (100)according to claim 17, wherein: the sheath (130) further comprises alow-friction layer (189), interposed between the reinforcement layer(187) of the sheath (130) and the corrugated outboard ply (112) of thebellows (108); and the low-friction layer (189) of the sheath (130) hasa surface roughness lower than that of the reinforcement layer (187) ofthe sheath (130).
 23. (canceled)
 24. The conduit (100) according toclaim 22, wherein: the bellows (108) further comprises a secondcorrugated outboard ply (114); the corrugated outboard ply (112) isinterposed between the corrugated inboard ply (110) and the secondcorrugated outboard ply (114); the second corrugated outboard ply (114)is hermetically coupled to the first inner collar portion (106) by thesecond weld (134) and is hermetically coupled to the second inner collarportion (107) by the fourth weld (184); and the low-friction layer (189)of the sheath (130) is in contact with the second corrugated outboardply (114) of the bellows (108). 25-27. (canceled)
 28. A conduit (200)for transporting a fluid, the conduit (200) comprising: a first collar(102) that comprises: a first outer collar portion (104); and a firstinner collar portion (106), threadably coupled with the first outercollar portion (104); a bellows (108) that comprises: a central axis(180); a corrugated outboard ply (112); a corrugated inboard ply (110),interposed between the corrugated outboard ply (112) and the centralaxis (180); and an interstitial space (126), interposed between thecorrugated inboard ply (110) and the corrugated outboard ply (112); afirst weld (138), hermetically coupling the corrugated inboard ply (110)and the first outer collar portion (104); a second weld (134),hermetically coupling the corrugated outboard ply (112) and the firstinner collar portion (106); and a first sensor (116), communicativelycoupled with the interstitial space (126).
 29. A method (300) offabricating a conduit (100), the method (300) comprising steps of:attaching a first tubular-outboard-ply end (149) of a tubular outboardply (113) to a first inner collar portion (106) of a first collar (102)with a second weld (134); attaching a second tubular-outboard-ply end(147) of the tubular outboard ply (113), which is axially opposite thefirst tubular-outboard-ply end (149) of the tubular outboard ply (113),to a second inner collar portion (107) of a second collar (103) with afourth weld (184); inserting a tubular inboard ply (111) into thetubular outboard ply (113) and advancing the tubular inboard ply (111)along an interior of the tubular outboard ply (113) until a firsttubular-inboard-ply end (157) of the tubular inboard ply (111) protrudesa first distance (D1) past the first inner collar portion (106), and asecond tubular-inboard-ply end (159) protrudes a second distance (D2)past the second inner collar portion (107), and wherein the firstdistance (D1) is greater than a first predetermined distance (PD1) andthe second distance (D2) is greater than a second predetermined distance(PD1); simultaneously corrugating the tubular inboard ply (111) and thetubular outboard ply (113) to form a bellows (108), having a centralaxis (180) and comprising a corrugated outboard ply (112), a corrugatedinboard ply (110), and an interstitial space (126), interposed betweenthe corrugated inboard ply (110) and the corrugated outboard ply (112),and wherein the corrugated outboard ply (112) is formed from the tubularoutboard ply (113), and the corrugated inboard ply (110) is formed fromthe tubular inboard ply (111); trimming a first corrugated-inboard-plyend (151) of the corrugated inboard ply (110), corresponding to thefirst tubular-inboard-ply end (157) of the tubular inboard ply (111), tocreate a trimmed first corrugated-inboard-ply end (156) that protrudesthe first predetermined distance (PD1) past the first inner collarportion (106); trimming a second corrugated-inboard-ply end (153) of thecorrugated inboard ply (110), corresponding to the secondtubular-inboard-ply end (159) of the tubular inboard ply (111), tocreate a trimmed second corrugated-inboard-ply end (170) that protrudesthe second predetermined distance (PD2) past the second inner collarportion (107); threadably interconnecting the first inner collar portion(106) and a first outer collar portion (104) of the first collar (102);threadably interconnecting the second inner collar portion (107) and asecond outer collar portion (105) of the second collar (103); attachingthe trimmed first corrugated-inboard-ply end (156) of the corrugatedinboard ply (110) to the first outer collar portion (104) with a firstweld (138); attaching the trimmed second corrugated-inboard-ply end(170) of the corrugated inboard ply (110) to the second outer collarportion (105) with a third weld (186); and communicatively coupling afirst sensor (116) with the interstitial space (126).
 30. (canceled) 31.The method (300) according to claim 29, wherein the first inner collarportion (106) is threadably coupled with the first outer collar portion(104) and the second inner collar portion (107) is threadably coupledwith the second outer collar portion (105) after the tubular inboard ply(111) is advanced along the interior of the tubular outboard ply (113)and after the tubular inboard ply (111) and the tubular outboard ply(113) are simultaneously corrugated. 32-38. (canceled)
 39. The method(300) according to claim 29, further comprising: flaring the firsttubular-outboard-ply end (149) of the tubular outboard ply (113) tocreate a first flared portion (148) of the first tubular-outboard-plyend (149), and wherein the step of attaching the firsttubular-outboard-ply end (149) of the tubular outboard ply (113) to thefirst inner collar portion (106) comprises attaching the first flaredportion (148) of the first tubular-outboard-ply end (149) to a firstbeveled weld-joint recess (144) of the first inner collar portion (106)with the second weld (134); and flaring the second tubular-outboard-plyend (147) of the tubular outboard ply (113) to create a second flaredportion (181) of the second tubular-outboard-ply end (147), and whereinthe step of attaching the second tubular-outboard-ply end (147) of thetubular outboard ply (113) to the second inner collar portion (107)comprises attaching the second flared portion (181) of the secondtubular-outboard-ply end (147) to a second beveled weld-joint recess(161) of the second inner collar portion (107) with the fourth weld(184).
 40. The method (300) according to claim 29, further comprising:attaching a first second-tubular-outboard-ply end (174) of a secondtubular outboard ply (115) to the first inner collar portion (106) withthe second weld (134); attaching a second second-tubular-outboard-plyend (176) of the second tubular outboard ply (115), which is axiallyopposite the first second-tubular-outboard-ply end (174) of the secondtubular outboard ply (115), to the second inner collar portion (107) ofthe second collar (103) with the fourth weld (184); and corrugating thesecond tubular outboard ply (115) simultaneously with the tubularinboard ply (111) and the tubular outboard ply (113) to form the bellows(108), which further comprises a second corrugated outboard ply (114);and wherein: the tubular outboard ply (113) is interposed between thetubular inboard ply (111) and the second tubular outboard ply (115), andthe second corrugated outboard ply (114) is formed from the secondtubular outboard ply (115).
 41. The method (300) according to claim 40,further comprising one of: selecting the tubular outboard ply (113) andthe second tubular outboard ply (115) to have equal lengths; or trimmingat least one of the tubular outboard ply (113) or the second tubularoutboard ply (115) so that the tubular outboard ply (113) and the secondtubular outboard ply (115) have equal lengths.
 42. The method (300)according to claim 40, further comprising: flaring the firstsecond-tubular-outboard-ply end (174) of the second tubular outboard ply(115) to create a third flared portion (178) of the firstsecond-tubular-outboard-ply end (174), and wherein the step of attachingthe first second-tubular-outboard-ply end (174) of the second tubularoutboard ply (115) to the first inner collar portion (106) comprisesattaching the third flared portion (178) of the firstsecond-tubular-outboard-ply end (174) to a first beveled weld-jointrecess (144) of the first inner collar portion (106) with the secondweld (134); and flaring the second second-tubular-outboard-ply end (176)of the second tubular outboard ply (115) to create a fourth flaredportion (182) of the second second-tubular-outboard-ply end (176), andwherein the step of attaching the second second-tubular-outboard-ply end(176) of the second tubular outboard ply (115) to the second innercollar portion (107) comprises attaching the fourth flared portion (182)of the second second-tubular-outboard-ply end (176) to a second beveledweld-joint recess (161) of the second inner collar portion (107) withthe fourth weld (184).
 43. The method (300) according to claim 29,wherein: the first outer collar portion (104) of the first collar (102)comprises a first annular weld-joint recess (145); the second outercollar portion (105) of the second collar (103) comprises a secondannular weld-joint recess (163); the trimmed firstcorrugated-inboard-ply end (156) of the corrugated inboard ply (110) isattached to the first annular weld-joint recess (145) of the first outercollar portion (104) by the first weld (138); and the trimmed secondcorrugated-inboard-ply end (170) of the corrugated inboard ply (110) isattached to the second annular weld-joint recess (163) of the secondouter collar portion (105) by the third weld (186). 44-48. (canceled)